chore(deps): bump actions/download-artifact from 4 to 6

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/opencv-cuda-artifact.yml

@@ -158,13 +158,13 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Download artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: opencv-cuda-release-python${{ env.PYTHON_VERSION }}-cuda${{ env.CUDA_VERSION }}-${{ github.sha }}
           path: ./artifacts
 
       - name: Download release info
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: release-info-python${{ env.PYTHON_VERSION }}-cuda${{ env.CUDA_VERSION }}-${{ github.sha }}
           path: ./artifacts